How Comprehensible Input Skyrocketed My Mandarin

Try Khov
7 min readSep 28, 2023

I’ve been studying Chinese Mandarin for about six years now and a good part of those years consisted of struggling to get pass the intermediate slump.

While I was amassing new vocabulary and grammar, they ultimately meant nothing when I could barely comprehend native speakers.

Determined to improve my listening, I sought the language learning community for new insights and methods.

I never expected that what I found would change the way that I approach language learning and ultimately, my life.

In late 2022, I stumbled upon Stephen Krashen’s Input Hypothesis, famously known as Comprehensible Input.

Brief Overview of Comprehensible Input (CI)

I won’t bore you with the technical details of this theory. If you’d like to learn more, here’s a great article that I found that explains it pretty well.

I will provide a brief overview and illustrate some examples of how you have been using practicing this theory your whole life.

According to Krashen:

“We acquire language in one way and only one way: when we understand messages. We call this comprehensible input.”

Okay, you may be asking:

How is this in any way profound?

To understand this, we first need to distinguish the difference between acquiring and learning.

Acquiring vs. Learning

In learning, we are taught grammar, conjugations, vocabulary, etc.
These are mechanical techniques that we are expected to memorize.

This is a very conscious practice.

But when you speak with your friends and family in your native language, how often do you consciously think about whether you’re using the correct conjugations or grammar structure?

Sure, you can argue that you’ve learned and internalized enough that it becomes natural.

But think a bit deeper.
Do you actually remember when you learned how to properly speak your native language? Did you read grammar books or learned conjugations to do so?

The answer is likely no.

While these methods may not be the reason you’re able to speak your native language, you’re still able to fluently speak it.

That’s because you acquired your language.

Language acquisition, more or less, is the subconscious process of language learning. Rather than learning through grammar and vocabulary, we learn through experiences, interactions, gestures, etc.

Take for example a baby.
Perhaps the first words they will learn is “mom” or “dad”.
While I’m not an expert on child development or neuroscience, I’d like to think that the child has subconsciously learned to associate their mother with the word “mom” without having to resort to a textbook.

Perhaps from your own experiences, you’ve learned words like “give” when someone sticks out their hand.

Before you didn’t know what it meant until someone explained it to you. Then you saw it frequently enough that you just learned what it meant.

Now, whenever you see this gesture, even if nothing was said, you’ll understand perfectly that this means to “give” or “hand over”. This is what Krashen means by “when we understand messages”.

Comprehension and i + 1

Next, let’s discuss an important condition that I think is absolutely necessary to succeed with this technique.

Krashen states clearly that we acquire language when we understand messages.

Obviously for us to comprehend, it means we understand. From the surface, this seems like circular thinking.

But take this example:
Have you ever stumbled across a phrase where you didn’t know all the words but you understood it perfectly? Like it just made sense?

Congrats, you’ve experienced CI at work. You didn’t need to know every word to understand the message.

And this is something that many of us at the start may have originally thought: To fully comprehend, we have to understand every word that’s said.

But that actually hinders our progress. On contrary, CI demands that we don’t understand every word for the method to work.

That’s where the concept of i + 1 comes in.

For mathphobes, don’t worry! This doesn’t dive deep into math.

i + 1 is really the concept of receiving input that’s slightly above your current level. i represents your current level and 1 represents a level above it.

No, you don’t have to take scientific tests to determine your comprehension level. Only you understand your comprehension abilities.

All i + 1 says is that to make CI effective, you need to challenge yourself to get input that’s slightly more advanced than where you currently are.

Input that’s too easy will bore you and input that’s too difficult will demotivate you.

While there are other important factors needed to make CI effective such as emotional state, I won’t get into them because I wanted to make this as brief as possible.

Before we move on, read this disclaimer.

I am not arguing that grammar, conjugations, and vocabulary are ineffective and a waste of time.

As a matter of fact, I believe that they are essential to your language learning journey.

But, I do believe that an over reliance on them can be detrimental. CI is merely another tool that complements these resources that you should take advantage of.

Now, let’s talk about how you can implement CI into your language routine.

How to Implement CI

First and foremost, everyone’s language learning process is different. What works for me may not necessarily work for you.

This is due to our individual learning preferences and the languages that we’re learning.

In this section, I’ll go over how I use CI to give you some ideas.

Identify Goals and Preferences

Before diving in and just consuming random content, it’s important to identify some of your goals and preferences:

What are your goals? Do you want to improve your reading? Listening?

Identifying your goals helps narrow down your focus.

For me, my goal was originally to improve my listening. This meant that I would consume content where people spoke native Mandarin.

To fully immerse myself, I’d turn on Chinese subtitles. Surprisingly, this then made me want to improve my reading. So now I’m trying to read more Chinese articles, books, and forums.

Learning how to read characters made reading subtitles easier, which made understanding shows easier!

Now that you’ve identified your goals, what type of media do you like to consume? (e.g books, movies, shows, video games, etc.)

The next step to implementing CI that works for you is to find content that entertains you.

Since I’m a visual learner that wants to improve my listening, I needed to consume content that I can see. This means watching movies, TV shows, playing video games, and books.

Because CI to me is more than just learning words, I needed content that had movement, gestures, and action. I learn more when I see how words are used in appropriate context.

And because I’ve identified my preferred content, I’ve excluded audio books and podcasts from my CI material.

It’s important that you find content that you enjoy consuming. Only then will CI be a sustainable routine.

Do you like horror movies or do you prefer romance? Even if you can’t find those types of native content in your target language, there may be translated or dub version of other shows or books.

For me, I watch shows on Disney+ or Netflix in Mandarin dub (or German and Spanish) because sometimes there aren’t many native Mandarin shows that I enjoy watching.

Initial Discomfort

To reinforce the i + 1 concept, CI is meant to challenge you. Like working out or learning a new skill, you have to challenge yourself to improve.

When I started watching Chinese shows, I often had moments where I didn’t understand anything. As a matter of fact, I still have those moments. But because I was opened to challenging myself, I learned so much faster than I anticipated.

Discomfort is part of the learning process. It helps to evaluate from time to time what you’re not understanding. Do the characters use too many technical terms? Or are they discussing a subject that you haven’t been exposed to?

Whatever it is, understand that it’s okay to not understand.

Sometimes it helps to look up words in a dictionary. Remember, you don’t need to understand every word, just enough to understand the message.

Limits of CI

I briefly mentioned in my disclaimer earlier that despite my praise for CI, vocabulary and grammar still have an integral role in language learning.

Vocabulary is important because you need words to understand your target language. However, you should not amass vocabulary for the sake of it or because a teacher tells you that you need to memorize them.

CI complements vocabulary because you learn words in context. When you understand the context, you can remember words easier because you recall the appropriate situations that they’re used in and the feelings that are evoked. Sometimes it helps to learn new vocabulary to better understand a situation.

Grammar is important because they provide structure to a language. You can’t simply say words and expect someone to understand you.

Grammar helps us understand what’s being emphasized, when and where something takes place, and how to express ideas.

I still refer to this Mandarin Grammar site when I need to review or learn how to say something correctly.

So while CI is great, it should not be the only tool in your toolbox.


It’s an understatement to say that CI has been effective for me. To some degree, I’d say that CI has changed my life.

My Mandarin comprehension has grown immensely because of it. Now, I don’t struggle as much to comprehend Mandarin content and I feel so much more confident speaking to native Mandarin speakers.

I can’t tell you the amount of times that I felt like I have a superpower. Whenever I’m able to understand a show or just understand what they were saying, it feels incredible that I don’t have to resort to English because this was something that I couldn’t do years ago.

I believe that CI is an essential tool in your language learning journey. You’ve already been using it for years now, you just didn’t know it.


  • Comprehensible Input (CI) is a subconscious language acquisition theory and method
  • We acquire language when we understand messages slightly above our current level (i + 1)
  • Do not over rely on vocabulary and grammar
  • CI does not substitute the use of learning vocabulary and grammar, it is merely a tool that complements them
  • Identify your goals and the types of content that you like
  • Discomfort and not understanding everything is a natural part of the process